Application of artificial intelligent technology in diagnostics the pulmonary sounds
研究生:周承漢 Cheng-Han Chou
指導教授:陳美勇 Mei-Yung Chen
關鍵字:肺音聽診 Pulmonary sounds analysis
類神經網路 Artificial neural network
小波轉換 Wavelet transform
接受器操作特性曲線 Receiver operating characteristic curve

  胸腔聽診為診斷肺部病症的主要方法,醫生藉由聽診器聽取肺部聲音,憑藉其專業認知與經驗來判斷不同的肺音所代表的病症。在120 Hz以下的生理訊號是由心音與肺音組成,而人耳對於低頻的靈敏度不高,故造成醫生在聽診判斷上的困難。為解決此一問題,本研究的目的為建構多種肺音辨識系統,用來辨識肺泡音(vesicular breath sounds),支氣管音(bronchial breath sounds), 氣管音(tracheal breath sounds),爆裂音(crackle),哮喘音(wheeze),喘鳴音(stridor)等六種常見肺音。
首先使用壓電麥克風與資料擷取卡NI-PXI 4472B擷取人體肺音訊號,並作訊號預處理。接著以小波轉換作為特徵擷取之方法,透過圖形監控軟體LabVIEW 設計小波轉換之架構,訊號分解後之六個頻段做標準差與平均值運算,以得十七個特徵值。在分類器方面,本研究以倒傳遞與學習向量量化類神經網路作為系統分類器之子系統,用以模擬網路之可行性與內部參數,再經由LabVIEW建構類神經網路,分別測試其網路分類率,最後整合各子系統並建構二階段式類神經網路,以提升系統之可靠度。由實驗結果顯示,相較於傳統聽診方式,本研究成功建構出一套多種肺音診斷系統,可正確地分類出六種常見肺部聲音,彌補人耳對於低頻靈敏度不高的缺點,並由圖形監控軟體LabVIEW建構人機介面,顯示肺音之頻譜、登記病歷資料等,可供醫生作為診斷肺部疾病病患之輔具。其結果顯示,本研究所建構之系統其辨識率可達95%。
  Chest auscultation is a main and efficient way to diagnose lung disease, it is a subjective process that depending on the physician’s experience and ability to differentiate between different sound patterns. Because physiological signals composed of heart sound and pulmonary sound are above 120HZ and the in sensitive of the human ear to the lower frequency, it is not easy to make diagnostic classification successful. In order to solve this problem, this study aims to construct a variety of pulmonary sound (PS) recognition system for classification of six different PS classes: Vesicular breath sounds, bronchial breath sounds, tracheal breath sounds, crackles, wheezes, stridor sounds.
  First, we use the piezoelectric microphone and data acquisition card NI-PXI 4472B to acquire PS signals, and signals preprocessing. The wavelet transform as feature extraction method, the PS signals were decomposed into the frequency subbands. Through statistical method we get the seventeen feature vectors which are used the neural network's input vector. This research used back-propagation (BP) neural network and learning vector quantization (LVQ) neural network to be  subsystem, and the two neural networks are integrated together as a two stage system that can increase the reliability. The neural networks' performance is verified by the receiver operating characteristic (ROC) curve. Comparing with traditional auscultation method, this study successfully construct a variety of pulmonary sound diagnostic system can correctly classify the six common pulmonary sounds. In this study, can be improved that human ear’s insensitive to the lower frequency, and show its pulmonary sounds wave, characteristic value and spectral analysis chart are shown by the human-machine interface design. By the research of this paper, the recognition rate of system is up to 95%.
    論文目次:目  錄
摘要      Ⅰ
致謝      Ⅲ
目錄      IV
圖目錄      VIII
表目錄      XII
第一章  緒論      1
1.1  前言      1
1.2  研究動機與目的    3
1.3  文獻回顧    4
1.3.1電腦化肺音診斷系統    4
1.3.2 訊號處理    6
1.3.3 肺音辨識    6
1.4  本論文之貢獻    9
1.5  論文架構    9
第二章  理論基礎    11
2.1  呼吸系統    11
2.2  肺音的發生機制    12
2.3  肺音種類區分    12
2.3.1支氣管音    13
2.3.2氣管音    14
2.3.3肺泡音    14
2.3.4哮喘音    15
2.3.5爆裂音    16
2.3.6喘鳴音    16
2.4  呼吸音與病理關係    17
2.5  小波轉換    21
2.5.1小波轉換的演進    21
2.5.2連續小波轉換    23
2.5.3尺度縮放與時間平移    24
2.5.4離散小波轉換    24
2.6  類神經網路    26
2.6.1學習策略    29
2.6.2網路架構    30
2.6.3類神經網路的特性    31
2.6.4學習效能    32
2.7  數位訊號處理及取樣原理    32
2.8  接受器操作特性曲線 (ROC Curve )    35
第三章  系統架構    38
3.1  系統整體架構    38
3.2  系統硬體    38
3.2.1系統之感測器    39
3.2.2麥克風性能參數    40
3.3  資料擷取卡    42
3.4  軟體架構    43
3.4.1特徵擷取單元    43
3.4.2分類器單元    44
第四章  系統架構設計與配置    46
4.1  肺音濾波與放大電路    46
4.2  母小波函數    47
4.3  多尺度分解    51
4.4  特徵擷取    52
4.5  類神經網路架構    53
4.5.1倒傳遞類神經網路架構    53
4.5.2倒傳遞靈敏度    59
4.5.3學習向量量化類神經網路架構    61
4.6  系統之分類器設計    63
第五章  實驗結果與討論      65
5.1  壓電麥克風頻率響應檢測    65
5.2  數位放大濾波電路    67
5.3  特徵值轉換    69
5.4  小波基底測試    69
5.4.1 Daubechies母小波測試結果    73
5.4.2 Coiflet母小波測試結果    74
5.4.3 Symlet母小波測試結果    76
5.4.4母小波測試之結果討論    77
5.5  類神經網路架構性能模擬    78
5.6  網路準確率評估    79
5.6.1倒傳遞網路準確率評估    79
5.6.2學習向量量化網路準確率評估    83
5.7  接受器操作特性曲線分析    86
5.8  二階段式分類器    87
5.9  人機介面功能    88
第六章  結論與未來展望      90
參考文獻      92
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